The present invention relates to a new and distinct cultivar of Hydrangea macrophylla and will be referred to hereafter by its cultivar name, ‘Hortmasun’. ‘Hortmasun’ represents a new big leaf hydrangea, a perennial shrub grown for landscape use.
‘Hortmasun’ was derived from an ongoing controlled breeding program directed by the Inventor in Boskoop, The Netherlands. The objective of the breeding program was to develop new cultivars of Hydrangea with bi-colored sterile flowers that are pink with white margins and that exhibit strong rooting. ‘Hortmasun’ arose from a controlled cross made by the Inventor in April of 2006 between unnamed and unpatented proprietary plants in the Inventor's breeding program; reference no. 03-015-06 as the female parent and reference no. 02-029-06 as the male parent. ‘Hortmasun’ was selected as a single unique plant from amongst the resulting seedlings in August of 2015.
Asexual propagation of the new cultivar was first accomplished by stem cuttings by the Inventor in Boskoop, The Netherlands in August of 2008. Asexual propagation by stem cuttings has determined that the characteristics of the new cultivar are stable and are reproduced true to type in successive generations.